Facsimile switching system



May 1, 1945. G. H. RIDINGS ETAL :FACSIMILE SWITCHINQSYSTEM .Filed Aug.25, 1942 INVENTORS G. H.RID\NGS F. I .CURRI E Patented May l, 1945-- YFACSIMILE SWITCHING SYSTEM Garvice H, Ridings, Summit, Vand Frank LeslieCurrie, Plainfield, N. J., assignors to The Western Union TelegraphCompany, New-York,

N'. Y., a corporation oiV New York Application August 25, 1942, SerialNo. 456,030

9 Claims.

'I'his invention relates to facsimile systems and has particularreference to systemswherein facsimile transmitting and recordingapparatus may be selectively interconnected for communication.

An object of the instant invention is toprovide an improved switchingsystem of greater ilexibility for use in interconnecting combinationtransmitter-recorders for communication.

Another object of the invention is to provide a switching arrangementwhereby the lines to a plurality of branch stations each havingcombination transmitter-recorders may be selectively connected to acombination transmitter-recorder at.

a central station.

Still another object of the invention is to provide a switching systemwhereby a central station combination transmitter-recorder may beconnected to any one of a plurality of lines terminating respectively inbranch stations, at each' of which is a combinationtransmitter-recorder, the switching operation being the same whether thecentral station initiates or answers a call. A better understanding ofthe invention may be obtained from the following description which istaken in conjunction with the accompanying drawing, of which:

Fig. l illustrates schematically an embodiment of the inventionutilizing a plug and jack switchboard; and

Fig. 2 shows a modification of the switching apparatus in which pushbutton switches are employed.

In Fig. l there is shown acentral station A and three branch stationsB,VC and D. The branch stations B, C and D are connected to the centrala station by line conductors II-IZ, |3-I4 and |5-|5, respectively, andeach pair of conductors terminates at the central station A in jacksI'l, i8 and I9, respectively.

The central station and each of the branch stations are each providedwith combination facsimile transmitters and recorders. The combinationtransmitter-recorder 2| at the central station is similar to thefacsimile apparatus located at each of the branch stations. Thisapparatus and the combination transmitter-recorder I2I,

combination transmitter-recorders 22| and 32| of 4stations C and D,respectively, are indicated in preceded by the numeral I.

the type disclosed in detail in an application of Wise et al., SerialNo. 293,188, filed September 8, 1939, now Patent No. 2,315,361, grantedMarch A3|), 1943. .Since such apparatus forms no part of the instantinvention, there is disclosed herein diagrammatically only enoughthereof to aiord an understanding of the illustrative embodiment of theinvention. The facsimile apparatus utilizes a Synchronous motor 22 todrive the shaft 23 and also a shaft 24 upon the engagement of a clutch'25. 'I'he apparatus disclosed in the Wise et al. case is modied for usein the present system by the introduction of a clutch between the shafts23 and 24. A cylinder 26 is secured to the shaft 24 for rotation therebyand serves to support a sheet for cooperation with a facsimile scanner2 1. When the machine is used as a transmitter, the sheet bearing theSubject matter for transmission is mounted upon the cylinder 26, and thescanner includes apparatus for generating facsimile signals inaccordance with the tonal densities of the subject matter in anywellknown manner. Also, when the apparatus is used' as a recorder, a.blank recording sheet is placed upon the cylinder 26 to receive marksplaced thereon by means of the scanner 2l, which in this case utilizesany well-known recording mechanism such as an electrical stylus, or asource of light where the recording is to be done by a photographicprocess. .A commutator 28 is also attached to the shaft 24 so that uponrotation the single conducting segment 29 bridges a pair of brushes 3|for a phasing or framing purpose to be described.

'I'he combination transmitter-recorder 2|. is also provided with asend-receive switch 32, by means of which the apparatus is arrangedeither as a transmitter or a. recorder. Such a switch will preferablyinclude additional contacts in `order to switch into operation theappropriate type station B, are shown diagrammatically, while the ofscanning apparatus. The transmitter-recorder 2| also includes astart-stop'switch 3,3 which, in its stop position, prepares an operatingcircuit for a buzzer 34 or other suitable alarm and, in its startposition, connects a source of alternating current` 35 to the drivingmotor 22 and to a rectifier 36. A relay 3l is also provided to transmita direct current signal over one of the line conductors. A relay 38 isconnected to be responsive to a direct current signal received over theother line conductor fora control purpose tobe described. y

I'he scanner 21 is connected through a pair oi direct currentblockingcondensers 39 `and 4| to conductors 43 and 44 which terminaterespectively in the sleeve and tip elements-of a switchboard plug 45.The plug 45 may be inserted Iin any of the jacks I'l, I8 and I9 wherebyconductors 43 and 44 are connected to a pair of linecon-y Thecombination transmitter-recorder 2| is of `6o ductors extending to oneof the branch stations.

Associated with each of the line jacks I1, I8 and |9 through normalcontactg thereof aresignal lights 46, 41 and 48. Thus, one terminal eLeach of the signal lights is normally connected respectively to one ofthe line conductors extending to each of the branch stations B, C and D.The other terminals of the signal lights are connected through thewinding of a relay 49, which is energized whenever one ormore of thesignal lights is energized, to close a circuit for the operation of analarm such as a buzzer The operating circuit for the buzzer 5| includesbreak contacts of a relay 52, the winding of which is inserted in one ofthe conductors, in this case conductor 44, connecting the combinationtransmitter-recorder 2| with the plug 45.

For a description of the operation of this system, assume that it isdesired to transmit by i facsimile from the central station A to one ofthe branch stations, for example, station B. The send-receive switch 32is operated to its send position; the plug 45 is inserted in the jackI1, and the start-stop switch 33 is operated to its start position.Immediately the motor 22 is operated to drive the shaft 23. Since atthis time the clutch magnet 53 is deenergized, the shaft 24 and theapparatus connected thereto -is held stationary in a predeterminedposition. The rectifier 36 is also energized by the operation of thestart-stop switch and, when it becomes completely operative, a circuitis completed from the positive terminal thereof through the winding of athermal relay 54 to ground. The negative terminal of the rectifier beinggrounded, the

thermal relay becomes energized. After this rerelay |36, to ground.

This relay operates and closes a circuit which includes the source ofalternating current potential |35, the start-stop switch |33, in itsstop position, the buzzer |34 and contact |58 ofthe relay. The attendantat station B, in response to the sounding of the buzzer |34 whichindicates ing circuit therefor and connects the alternating currentsource |35 to energize the rectifier |36 and the motor |22. In thiscase, as soon as the rectifier becomes operatively conditioned, acircuit ls completed 'from the positive terminal thereof through theclutch magnet |53 and the make contact |59 of relay |38 to ground,thereby engaging the clutch to rotate the shaft |24 and the apparatusconnected thereto including the commutator |28. When the contact |55 ofthe thermal relay |54 is closed, the positive terminal of the rectifieris connected to one terminal of the winding of relay |31, which does notnecessarily operate immediately because of the rotation of thecommutator |28. Upon the engagement of the brushes |3| with theconducting segment |29, following the closure of the thermal relaycontact, a circuit is completed through the the buzzer.

winding of relay |31 and the send-receive switch |32, in its receiveposition, therebyoperating the relay, which locks through its contact|56 and connects positive direct current potential through its contact|51 to line conductor l 2.

At the central station A, the positive direct current potential onconductor I2 is communicated through the tip elements of the jack |1 andthe plug 45 and is extended through Ithe winding of relay 52 and overconductor 44 to the winding of relay 38. The latter relay operates and,by means of its contact 59, completes a circuit through the clutchmagnet 53. The clutch 25 is thus engaged to initiate rotation of shaft24 and the apparatus connected thereto so that accurate framing betweenthe transmitting cylinder 26 yand the re- A`ceiving cylinder |26 iseffected.

The'facsimile signals generated by the scanner 21 are transmittedthrough the switching apparatus to station B where they are employed tooperate the recording scanner |21 in a well-known manner.

When it is desired to transmit by facsimile from one of the branchstations to the central station, the attendant at the branch station,such as station B, operates the send-receive switch |32 to its sendposition and the start-stop switch |33 to its start position. As in thepreviously described case, the motor |22 immediately starts, but in thiscase it rotates only the shaft |23, since the clutch |25 is disengagedby reason of the incomplete operating circuit therefor at the contact|59 of relay |33. Following the closure of the contact |55 of thethermal relay |54 and the closure of contact |51. of relay |31, positivedirect current potential is impressed upon the line conductor I2. At thecentral station A this positive potential is extended through the normalcontact of jack |1 through the lamp 46 and the winding of relay 49,thereby operating the lamp and the relay. The closure of contact 6| ofrelay 49 completes a circuit including a source of energy 62 and thebreak contact 63 of relay 52 to sound the buzzer 5|. The attendant atthis station, responding to the call thus initiated, inserts the plug 45in jack |1 in accordance with the indication given by the lamp 46 andoperates the'send-receive switch 32 of the combinationtransmitter-recorder 2| to its receive position and the start-stopswitch 33 to its start position. The extension of the line conductor I2through the tip elements of the jack |1 and the plug 45 impresses thedirect current potential upon the windings of relays 52 and 38, therebycausing the operation of these relays. The insertion of the plug 45 inthe jack `|1 opens the normal contactof the latter, therebyextinguishing the light 46 and deenergizing the relay 49, the latteroperation resulting in the silencing ofthe buzzer 5|. The opening ofcontact 63 of relay 52 conditions the operating circuit of the buzzer 5|so that any incoming calls while the transmitter-recorder 2| is busywill operate one of the signal lights 41 or 48 and also the relay 49,but the latter operation willv not sound It will be noted that thebuzzer is prevented from operating while the central stationtransmitter-recorder 2| is busy irrespective of whether it is used as atransmitter or a recorder for the reason that in either case there isconnected to conductor 44 a direct current potential during theoperative-condition of the facsimile apparatus to cause the operation ofrelay 52.

The transmitter-recorder 2| arranged as a recorder operates in the samemanner 'as the previously described operation of the transmitterrecorder|2I at station B when arranged as a recorder. Relay 31 is operated underthe control of the commutator 28 at a predetermined point in arevolution of the cyinder 26 to connect positive direct currentpotential by means of its contact 51, conductor 43, the sleeve elementsof the plug 45 and the Jack |1 and line conductor to relay |38 atstation B. The closure of contact |59 of this relay energizes the clutchmagnet |53 to effect the engagement of the clutch |25 and to initiaterotation of the cylinder |26 in a manner similar to that previouslydescribed.

Instead of the plug and jack switchboard apparatus for selectivelyconnecting the 4central station facsimile apparatus to that of any ofthe branch stations, Fig. 2 illustrates an arrangement using push buttoncontrolled contacts for this purpose. Contacts controlled respectivelyby push buttons 64, 85 Aand 66 are used to selectively connect lineconductors ||-|2, |3'|4 and |5 I6 to conductors 43 and 44 extending tothe combination transmitter-recorder A2|. These push buttons are of thetype which, when operated, are locked in such position and are releasedby unlocking upon the operation of another push button. Each of the pushbuttons such as 64 is provided with a cam surface 61 which, uponoperation of the push button, moves a bail member 68 against arestraining member such as a spring 69 so that a flange 1| of the bailmember is moved to permit the lobe of the push button vcam to be movedbeyond the flange. The flange 1| is then moved under the influence ofthe spring 69'to engage a portion of the cam lobe whereby the pushbutton is held in its operated position. The push button is held in suchposition until one of the other push buttons such as 65 is similarlyoperated to again move the bail member 68 suiciently to allow the camlobe of the push button 64 to become disengaged from the ange 1|. 'I'henewly operated push button 65 is then locked in its operated position ina manner similar to that in which Apush button 64 is locked. Such astructure or an equivalent thereof is conventional and is shown hereinas embodying a.

bail member having a plurality of flanges such as 1| for ease ofillustration. Preferably, the push buttons should be arranged in ahorizontal row whereby the cam lobes thereof would be aligned, therebymaking it possible to use a bail member having but a single flangeextending along the aligned push button cam lobes.

Whether for the purpose of initiating a call from the central station Aor for answering a call from one of the branch stations B, C or D, thepush button associated with the line extending to the branch station isoperated for the purpose of connecting the line conductors to thevconductors 43 and 44 extending to the central stationtransmitter-recorder 2|. For example, line conductors and I2 extendingtothe branch station B are connected by means of make contactsassociated with the push button 64 to the conductors 43 and 44 in anobvious manner. Also, in response to the initiation of a call from oneof the branch stations such as station C, for example, direct currentpotential is impressed upon line conductor |4 and through a normalcontact associated with the push button 65 is extended through the lamp41 and the winding of relay 49, thereby indicating the call to beanswered. In this case, the call is answered by operating indicated,both conductors have impressed therel on direct current potentialsduring operative conditions of the transmitter-recorder 2|.

Since any push button remains locked in its operated positionv untilanother push button is operated, the line conductors associated with anoperated push button are left connected to the central stationtransmitter-recorder 2| after this A apparatus and the branch stationapparatus connected to the line conductors have been placed intheir idleconditions. For example, when push button 64 is operated, thetransmitter-recorder |2| of branch station B is connected to thetransmitter-recorder 2| of the central station A. After the exchangeofcommunication between these two stations, the respective apparatus'thereat is stopped by placing the respective startstop switches 33 and|33 in their stop positions. If, while these conditions exist, branchstation C desires to transmit to the central station A, the call iseected over line conductor' I4 to operate` the lamp 41 and energize therelay 49. Since th'/ central station transmitter-recorder 2| is idle,there are no direct current potentials connected to conductors 43 and 44so that relay 52 is deenergized and thereby permits the operation of thebuzzer 5| in response to the operation of relay 49. The usualindications of the call from fbranch station C are therefore given, andthe call is answered by the operation of push button 65.

However, if while push button 64 is operated during an idle periodbranch station B desires to transmit to the central station A, theconnection of direct current potential to line conductor I2 will notoperate the lamp 46 or the relay 49, but by reason of the extension ofthe line conductor I2 through the operated contacts associated with thepush button 64 over line conductor 44, relay 38 is operated at thetransmitter-recorder 2| The closure of contact 58 of this relay.energizes the buzzer 34 associated with the facsimile apparatus andthereby indicates to the attendant at station A that the branch stationalready connected to the'facsimile apparatus at the central stationdesires to transmit. The attendant then places the send-receive switch32- in its receive position and operates the start-stop switch 33 to itsstart position, and the apparatus functions in the usual manner.

The nature of the invention may be ascertained from the foregoingdescription of two illustrative embodiments, it being understood thatchanges in the invention herein disclosed may be made within the scopeof what is claimed without departing from the spirit of the invention.

What is claimed is:

1. In a facsimile system, a central station, a plurality of branchstations, similar combined transmitter-recorders at all of said stationseach of said transmitter-recorders comprising a common copy holder anddriving mechanism therefor, individual communication circuits connectingeach of said branch stations with said central station, and switchingmeans at said central station to connect selectively said centralstation transmitter-recorder for either transmitting or recordingcommunication with the transmitterrecorder at any one of said branchstations,

2. In a facsimile system. a central'station, a plurality of branchstations, similar combined transmitter-recorders at all of said stationseach of said transmitter-recorders comprising a cornmon copy holder anddriving mechanism therefor, individual communication circuits connectingeach of said branch stations with said central station, and switchingmeans for connecting selectively any of said communication circuitsA tosaid central station transmitter-recorder for communication either to orfrom said central station.

3. In a facsimile system, a central station, a plurality of branchstations, similar combined transmitter-recorders at all of said stationseach of said transmitter-recorders comprising a common copy holder anddriving mechanism therefor, individual communication circuits connectingeach of said branch stations with said central station, switching meansfor connecting selectively said central station transmitterrecorder toany of said communication circuits, and means employing said selectiveconnection for transmitting to the branch station associated with theconnected one of said circuits when said central stationtransmitter-recorder is arranged for transmission and for receiving fromthe connected branch station when said central stationtransmitter-recorder is arranged for receiving.

4. In a facsimile system, a central station, a plurality of branchstations, similar combined transmitter-recorders at all of saidstations, individual communication circuits connecting each of saidbranch stations with said central station, means at said central stationfor connecting selectively said central station transmitter-recorder toany one of said communication circuits, means utilizing direct currentpotentials on corresponding conductors of said communication circuitsfor placing calls for connections to the respective ones of saidcircuits, indicating means at said central station individuallyassociated with each of said communication circuits and each responsiveto said direct current calling signal, and means including saidconnecting means and utilizing a direct current potential on the otherconductor of the calling communication circuit for synchronizing thefacsimile apparatus at the connected stations.

5. In a facsimile system, a central station, a plurality vof branchstations, similar combined transmitter-recorders at all of saidstations, individual communication circuits connecting each of saidbranch stations with said central station, connecting means at saidcentral station for placing said central station transmitter-recorder incommunication with the transmitter-recorder at one of said branchstations, individual indicating devices normally responsive to directcurrent potentials applied to corresponding lconductors of each of saidcommunication circuits forcalling purposes, a signal responsive devicecommonly associated with all of said indicating devices and normallyresponsive to a calling direct current signal received over any of saidcommunication circuits, means including said connecting means operablein answering a call for releasing the individual indicating deviceassociated with the calling circuit and also said common signalrespcnsive device, and means controlled by a direct current potentialapplied to one of the conductors of said connected communication circuitfor disabling said common signal responsive device for the duration ofthe communication.

6. In a facsimile system, a central station, a plurality of branchstations, similar combined transmitter-recorders at all of saidstations, individual communication circuits connecting each of saidbranch stations with said central station, connecting means at saidcentral station for placing said central station transmitter-recorder incommunication with the transmitter-recorder at any one of said branchstations, individual indicating devices normally responsive to directcurrent potentials applied to corresponding conductors of each of saidcommunication circuits for calling purposes, a signal responsive devicecommonly associated with all of said indicating devices and normallyresponsive to a calling direct current signal received over any ofvsaidcommunication circuits, means including said connecting means operablein response to a call for releasing the individual indicating deviceassociated with the calling circuit and also said common signalresponsive device, and means also including said connecting means fordisabling said common signal responsive device.

7. In a facsimile system, a central station, a plurality of branchstations, similar combined transmitter-recorders at all of saidstations, individual communication circuits each comprising a pair ofconductors connecting each of said branch stationswith said centralstation, means at said central station for extending any pair ofconductors to said centralstation transmitterrecorder, individualindicating devices normally associated with corresponding conductors ofeach of said communication circuits and responsive toirect currentpotentials applied to said conductors for calling purposes, a signalresponsive device commonly associated with all of said indicatingdevices and normally responsive to a calling signal received over any ofsaid communication circuits, means including said conductor extensionmeans for disabling the indicating means associated with the extendedpair of conductors for the duration of said extension, and means alsoincluding said'conductor extension means for disabling said commonsignal responsive device for the duration of the communication.

l8. The invention deiined in claim '7 further characterized by, meansincluding the indicating device associated with a non-extended pair ofconductors foiindicating during the extension of another pair ofconductors the receipt of a call from the branch station connected tosaid nonextended pair of conductors.

9. The invention defined in claim '7 further characterized by, a signalresponsive device associated with said central stationLtransmitter-recorder, and means including said transmitterrecordersignal responsive device for indicating during the extension of a pairof conductors to said central station transmitter-recorder the reto saidextended pair of conductors.

GARVICE H. RIDINGS. FRANK LESLIE CURRIE.

